I tried to used mailmerge actually, but I was blocked because the generated document was not "dynamic" and the mailmerge function creates me 1 Word document for each line in the Excel document.
The fields were static, and that was not what I was looking for.

Here's the structure of my Excel file :
Phase ----- Phase Description ----- Phase Beginning date ----- Phase Ending date ----- Phase ressources


In addition to that, I would need to have a global field for the following fields :
Document Reference
Document Date
Read by (name of verificator)
Writed by (name of writer)

And this would create a Word composed of a title (Document Reference) a first page containing my document information (date, reader, writer, brief introduction), then a summary with the content of the document, which would be composed of :
I. Phase 1
--- Description Phase 1
--- Date Phase 1
--- Ressources Phase 1

II. Phase 2
--- Description Phase 2
--- Date Phase 2
--- Ressources Phase 2

...

And so on, depending on the number of line of the Excel document.

Did I made my point clear ? It's not easy to explain in english, as I'm french :P

Thanks anyway !